This invention relates to a storage system composed of a host computer, a storage subsystem and a management computer and, more specifically, a technique of monitoring copy pairs.
The development of information-oriented society has resulted in the introduction of computer systems everywhere, and the amount of data processed by individual computer systems is growing at an explosive rate. Another result of the advance of information-oriented society is the enhanced importance given to data that is handled by computer systems and data stored in computer systems is demanded to be high in reliability. Data stored in computer systems has to be protected against all kinds of disaster, and it is a responsibility to society to prevent the loss of data stored in computer systems.
Such the computer systems ensure data reliability by storing the same data in multiple volumes. Data outputted from a host computer which executes processing is not only stored in a volume within a storage subsystem that is connected directly to the host computer but also copied to another volume to be duplicated.
Copy between a source volume and a target volume that are in the same storage subsystem is commonly called local copy, whereas copy between a source volume and a target volume that are in different storage subsystems is called remote copy. Local copy and remote copy are employed in computer systems that are required to have high reliability.
Local copy and remote copy are collectively called replication. Replication enables a computer system to continue operating when a failure in one volume renders this volume inoperative with the use of data stored in the other volume.
Two volumes associated with each other by replication, that is, a source volume and a target volume, are called a copy pair. The host computer stores definition information of volumes forming a copy pair to operate the copy pair and obtains information on the status of the copy pair based on the definition information.
For example, US 2005/114467 A discloses techniques which allow a host computer to obtain replication status information of a remote site storage subsystem that is not directly connected to the host computer.